1. Field of the Invention
This invention relates to processes for imparting smooth-dry and flame retardancy to cotton fabrics.
2. Description of the Prior Art
Cotton by itself does not possess either smooth-dry (DP) or flame retardance (FR) characteristics. In order for cotton to acquire these properties, cotton must be given a chemical finish. In the case of smooth dry performance, this is achieved by the crosslinking of cotton using one of the well-known crosslinking agents such as dimethylol dihydroxyethyleneurea.
In the case of flame retardancy, performance is achieved by applying finishes that add concentrations of compounds that contain elements which have been found to be effective in improving the fire resistance of cotton. Two systems are frequently employed. One system is based on finishes that add a combination of phosphorus and nitrogen to the fabric while the second utilizes a combination of antimony and halogen.
In the case of phosphous-nitrogen finishes, a well-known finish is the so-called THPOH--NH.sub.3 [tetrakis(hydroxy methyl)phosphonium hydroxide-ammonia] finish. In this case, the THPOH is padded onto the fabric, the fabric is dried and the fabric is treated with gaseous ammonia. Subsequently, the fabric is oxidized. Attempts to give this fabric a durable-press finish by application of a crosslinking agent are generally unsuccessful because the crosslinking agent is reactive with the free --N--H groups in the THPOH--NH.sub.3 polymer rather than the OH groups of cellulose. Similarly, pretreatment of the fabric with crosslinking agent prior to FR finishing, generally renders the FR treatment ineffective.
The other systems utilized to make cotton fabrics flame retardant are based upon the use of compounds containing antimony and halogen. Typically, the antimony is added to the fabric in the form of antimony oxide. The halogenated component is added either in the form of halogenated polymers or as in small discrete inert halogenated compounds such as decabromo diphenyl oxide. Both the antimony and small discrete halogenated compounds are retained on the fabric by means of being trapped in the fabric by the use of added polymers in the finish. Polyacrylates are frequently used for this purpose. The high add-ons of polymers in this finish tends to lead to a stiff fabric.